242 DIPTERA OF NORTH AMERICA. [PART II. 



that we are induced to take it for a specimen of the latter with a 

 hut little developed picture of the wings, unless much stress is laid 

 upon the circumstance, that Walker calls the appendages of the 

 hypopygium * dark pitchy" while they are of a hrown-black color, 

 even in specimens the color of which is but little developed. 



19. chrysoprasi Walk. Described without statement of the sex. The 



description agrees tolerably well with a species from Cuba, only the 

 statement about the color of the feet does not agree entirely. 

 Nevertheless I believe it to be the species of Walker; I have de- 

 scribed it below with the necessary change of its name in P. chryso- 

 prasius. 



20. suavium Walk. Described without stating the sex, evidently a spe- 



cies with black feet, which belongs to the relationship of patibulatus 

 Bay ; the description contains no characters which would assist in 

 determining this species. 



21. amatus Walk. Male and female. The remarkable statement, that 



the abdominal segments of the male have black bands on their pos- 

 terior margin, agrees with no species known to me, and probably 

 with no species of Psilapus whatever, because the black abdominal 

 bauds, apparent in so many species, are always found on the ante- 

 rior margin of the segments. Mr. Walker means, perhaps, the nar- 

 row margins on the posterior border of each segment, which, when 

 seen in a certain light, have a black appearance ; or he may have 

 simply made a mistake in stating " posterior margin" instead of 

 "anterior margin." Besides this doubtful statement, all the rest 

 agrees so well with specimens of patibulatus, with faded outlines of 

 the picture of the wings, that amatus Walk, must be taken for a 

 synonym of this species, until more satisfactory marks of distinc- 

 tion to separate it from patibulatus are found. 



22. inficitus Walk. Mr. Walker makes no statement about the sex of 



the specimen ; as however in the group to which this species belongs, 

 the halteres of the males are usually black, and those of the females 

 are usually yellow, we may conclude that it was a male. This 

 being admitted, its description contains no character whereby infi- 

 citus could be distinguished from dark-colored males of patibulatus, 

 and therefore it must be placed at present among its synonyms. 



23. nigrofemoratus Walk. Described without statement of the sex, 



probably after a male related to scobinator. One variety, &, is said 

 to be distinguished by the tip of the femora and the whole tibia? 

 being yellow. It is easy to perceive that this is no variety, but a 

 different species, and probably the male of ine.rmis, which will be 

 described further below. As in this species the tips of the fore and 

 middle femora only are yellow, therefore the femora of nigrofemora- 

 tus Walk., in conformity with its description, must be of an entirely 

 dark color; thus nigrofemoratus cannot be mistaken neither for 

 scobinator, nor calcaratus, nor caudatus, the femora of wliich are pre- 



